Numerical simulations of counterflow non-premixed $CH_4/C_2HCl_3/Air$ flames added 8%(by volume) C2HCl3 on the fuel side are conducted at atmospheric pressure using a detailed chemical reaction mechanism in order to understand the effect of strain rates. A detailed sensitivity analysis is also performed in order to assess the relative influence of each reaction on the flame established at a strain rate of 200s-1. The structure of flames (i.e., temperature, velocity, and concentration of species) established at both a strain rate of 150s-1 and 300s-1 are investigated. As the strain rate increases, the "flame zone" is restricted to a narrower range and the position of maximum temperature is shifted to the fuel side. The concentrations of major species, H2O, CO, H2, HCl, Cl2, and Cl are decreased with increased strain rate. The reaction involving chlorine, CH4 + Cl $ ightarrow$ CH3 + HCl, instead of the reaction, CH4 + H $ ightarrow$ CH3 + H2 influences the consumption of methane. C2HCl3 + OH $ ightarrow$ CHCl2 + CHOCl and HCl + OH $ ightarrow$ H2O + Cl, are major reactions, through which OH radicals are consumed.